Driveline sealing components are frequently used for covering the chamber of a joint that is filled with a lubricating agent. The sealing components prevent lubricating agents from leaving the joint chamber while preventing dirt and other contaminants from entering the joint chamber.
One application that utilizes sealing components is constant velocity joints. A constant velocity joint is used to transmit rotating power from one joint member to the other joint member so as to rotate at a constant velocity while allowing the above two joint members to freely deflect the axial center lines thereof from each other within a predetermined angle range.
When the constant velocity joint is used in a driveline system of a vehicle, the joint portion of the constant velocity joint is typically covered with a boot. The boot is flexible and generally has a deformable shape such as bellows. A typical boot includes a first relatively large end that is secured to an outer race of the constant velocity joint and a second relatively small end that is secured to the shaft extending from the inner race of the constant velocity joint. In other words, one open end of the boot is positioned on the outer periphery of one joint member while the other open end is positioned on the outer periphery of the other joint member.
In the boot of this type, adjacent folds locally come in contact with one another when the constant velocity joint rotates at a high velocity with a large joint angle. As a result, wear occurs in the boot, reducing the sealing effectiveness of the boot, and shortening the effective life of the boot. One known solution to overcome the wear problems is to include wax in the boot to smooth the outer surface of the boot. However, undesirable wear still occurs, especially in high temperature applications.
Another solution to undesirable wear problems for high temperature applications that is known to the present inventor is the use of hydrogenated nitrile butadiene rubber (HNBR) material, as described in co-pending U.S. patent application Ser. No. 10/912,400, incorporated herein by reference in its entirety. HNBR material is useful in applications having a peak temperature of 150° C. peak, or 130° C. continuous. Accordingly, there is a need for a boot that is capable of withstanding higher temperatures (i.e., greater than 150° C. peak temperatures), as well as high-speed, and high-angle applications.